Sylvania



April 2, 1 929. G; E. DREsER 1 AB'RA'S IVE S TONE Filed Sept. 17, 1924 Patented Apr. 2, 1929.

' UNITED STATES PATENT OFFICE.

GEQRGE E. DRESSER, or: NIAGARA FALLS, NEW YORK, ASSIGNOIR. TO THE CARBO- RUNDUM COMPANY, OF NIAGARA FALLS, NEW YORK, CORPORATION OF PENN- sYLvAnrA.

' ABRASIVE s'ronn.

Application filed Sentember 17, l9 24.- Serial Ho.-738.161.

The present invention relates to abrasive stones and particularly to abrasive stones for dressing or sharpening vibrator or contact points in automobile ignition systems.

IIT the magneto system the contact points are made of platinum and can be dressed with a thin file especially made for such purpose. In the battery system, however, the contact points are m'ade'of tungsten steel and a file has practically no effect on them. Therefore,

the only way to dress them is with an abrasive stone. 1

Abrasive stones have been put out for this purpose having a tapered shape and tapering down to about 1 g in thickness. These stones I can onl be used on the extreme :point and broken in use or when thrown around in av tool kit.

' By the present-invention I overcome this I difiiculty by providing the abrasive stone of uniform thickness with a metal reinforcement along one edge thereof. This reinforce ment is made thin enough so as not to interfere with-the insertion of the stone into different types of mechanism. andit covers only a small part of the width of the stone. Thisreinforcement, running substantially the full length of the stone, enables it. to be thrown about or dropped on the floor with small liability of the stone breaking. If a piece is .-broken off of the'end of the stone, the metal reinforcement can becut off and the stone can then be used like a new stone. I Y

This type of stone is particularly advantageous because it can be inserted and operated with any of the usual types of vibrator mechanisms and it is possible with this stone having parallel. sides and uniform thickness, to dress off two abutting contact points at the same time, that is, with one insertion of the stone. This saves considerable time as it is possible with this reinforced stone to dress two points in from two to three minutes where previously it tookfrom fiveflto seven minutes.

In the accompanyin drawings wherein I have illustrated a pre erred embodiment of my invention-Figure 1 is a perspective new tudinal edges of the stone I provide a metal reinforcement 3 extending substantially the full length of the stone. This reinforcement is preferably made of thin sheet metal bent into the form of a channel so as to grip the opposite faces of the stone. The friction between the reinforcement and the faces of the stone will ordinarily hold thereinforcement on thestone but, if desired, the reinforcement may be additionally secured by means of cement. The reinforcement is made suflicientlythin so as not to interfere with the use of the stone and it is made to extend only over a small portion of the Width of the stone on the opposite faces thereof.

This reinforcement prevents breaking or chipping of the stone under ordinary conditions and in casean end portion of the stone does become broken from the main body of the stone the projecting portion of the metal reinforcement can be readily cut off and the stone used like a new stone.

While I have shown a preferred manner of reinforcing the stone it will be understood that the invention is not limited to the exact form shown but that it may be modified Within the scope of the appended claims.

- I claim: 1. As a new article of manufacture, a

abrasive stone for use as a file for dressing the contact points of automobile ignition 'systerns, consisting of a strip of abrasive stone of substantially uniform thickness of about 1 g inch throughoutits length and which is thin enough to pass between the contact points of such ignition systems but not thick enough f to withstand the use to which it is to be put 2 without breaking, and a sheet metal reinforcingmember of channel form closely fitting over one edge of the strip along substantially its full length, said reinforcing member extending over a small portion only of the width of the stone and being sugficiently thin so 2 mom'ia as not to interfere with the use of the stone fitting over one edge of the strip along subin dressing the contact points of automobile stantially its full length, said reinforcing ignition systems. member extending over a small portion only 2. As a new article of manufacture, an ofthe Width of the stone and. being sufficiently 1 5 abrasive stone for use as a file for dressing thin so as not to interfere With the use of the the contact points of automobile ignition sysstone in dressing the contact points of autotems consisting of a strip of abrasive stone mobile ignition systems. l i

of substantially uniform thickness and thin In testimony whereof I have hereunto set enough to pass between the contact points of my hanol. o 10' such ignition systems and a sheet metal reinforcingmember of channel form closely GEORGE E. DRESSER. 

